This rotator is at Washington and Lee University in
Lexington, Virginia.

The rotator at the right is from the Lawrenceville School
in New Jersey. It was made by the firm of L. E. Knott of Boston, and is listed
as the "Ziegler Twenty-One Pound Mechanical Rotator or Whirling Table" at
a cost of $6.95 in the 1916 catalogue

The accompanying text reads: "It is made of cast iron,
all parts neatly japanned, and may be used in either a vertical or a horizontal
position.... Furnished with each rotator are the various attachments for
fastening the accessories. Thus there will be found with each instrument a
universal chuck for fastening objects with a spindle; also a special lock-nut
head designed for fastening plates, color disks, etc., for attaching the string
of such accessories as the Disc, Egg and Chain."

At the left is another Knott Rotator, this time from
the Virginia Military Academy.

The rotator at the right is from Colby College, and
is unmarked. It is probably late nineteenth century.

The rotator above I bought for the use of the Kenyon
College Physics Department at a shop selling antique tools. It was advertised
as a drive mechanism for a dentist's drilling engine! The arrangement of
feet on the left-hand side show that it can be used vertically or horizontally.
It is often used in lecture demonstrations driving a circular table with an
arrow attached to its top to illustrate simple harmonic motion by shadow projection.

At the left is a clockwork rotator I photographed
at Colby College in Waterville, Maine in 1978. It is by Jung of Heidelberg.

This is a large picture of a small device! It is
part of the Simple Harmonic Motion Demonstration Apparatus listed in the 1929
Central Scientific Company for $12.00 The entire apparatus consisted of a
metal disk about 16 cm diameter, with the device at the left mounted 7 cm
from the center. The "V" was oriented in the direction of the tangential velocity,
and the "A" pointed inward, showing the direction of the centripetal acceleration.
The system was illuminated from the side by a broad beam of light, and the
shadows of the letters were cast on the wall as the ball moved back and forth
in simple harmonic motion.

The device, which can be easily made for lecture demonstrations,
is in the Greenslade Collection.

The rotator at the top left and the accessories in the photograph
below it are in the apparatus collection of the physics department of Hobart
and William Smith Colleges in Geneva, New York. They were bought in the
later 1920s from Max Kohl of Chemnitz, Germany.

The rotator (or whirling trable) has a table-edge clamp so
that it may be used securely in a vertical postion.

The large and small balls on the horizontal sliding rod is
the demonstration showing that a two body system will rotate about its center of mass.

The rotator at the right is at Case Western Reserve University
in Cleveland, Ohio. It is small (only 32 cm long) and unmarked.

Clearly the rotating ring is meant to hold something, although
when I examined it closely it contained no holes for attaching a gyroscope
or a suspended solid. For the present, this is a mystery piece of apparatus.